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From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
To: Finn Thain <fthain@telegraphics.com.au>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
	Kees Cook <keescook@chromium.org>,
	Jakub Kicinski <kuba@kernel.org>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
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	Nathan Chancellor <natechancellor@gmail.com>,
	Miguel Ojeda <ojeda@kernel.org>, Joe Perches <joe@perches.com>
Subject: Re: [PATCH 000/141] Fix fall-through warnings for Clang
Date: Mon, 23 Nov 2020 15:05:31 +0100
Message-ID: <CANiq72=z+tmuey9wj3Kk7wX5s0hTHpsQdLhAqcOVNrHon6xn5Q@mail.gmail.com> (raw)
In-Reply-To: <alpine.LNX.2.23.453.2011230938390.7@nippy.intranet>

On Sun, Nov 22, 2020 at 11:54 PM Finn Thain <fthain@telegraphics.com.au> wrote:
>
> We should also take into account optimisim about future improvements in
> tooling.

Not sure what you mean here. There is no reliable way to guess what
the intention was with a missing fallthrough, even if you parsed
whitespace and indentation.

> It is if you want to spin it that way.

How is that a "spin"? It is a fact that we won't get *implicit*
fallthrough mistakes anymore (in particular if we make it a hard
error).

> But what we inevitably get is changes like this:
>
>  case 3:
>         this();
> +       break;
>  case 4:
>         hmmm();
>
> Why? Mainly to silence the compiler. Also because the patch author argued
> successfully that they had found a theoretical bug, often in mature code.

If someone changes control flow, that is on them. Every kernel
developer knows what `break` does.

> But is anyone keeping score of the regressions? If unreported bugs count,
> what about unreported regressions?

Introducing `fallthrough` does not change semantics. If you are really
keen, you can always compare the objects because the generated code
shouldn't change.

Cheers,
Miguel

  parent reply index

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-20 18:21 Gustavo A. R. Silva
2020-11-20 18:28 ` Joe Perches
2020-11-20 19:02   ` Gustavo A. R. Silva
2020-11-20 18:40 ` [PATCH 134/141] video: fbdev: lxfb_ops: " Gustavo A. R. Silva
2020-11-22 22:05   ` Sam Ravnborg
2020-11-24 14:44     ` Gustavo A. R. Silva
2020-11-20 18:40 ` [PATCH 135/141] video: fbdev: pm2fb: " Gustavo A. R. Silva
2020-11-20 18:53 ` [PATCH 000/141] " Jakub Kicinski
2020-11-20 19:04   ` Gustavo A. R. Silva
2020-11-20 19:30   ` Kees Cook
2020-11-20 19:51     ` Jakub Kicinski
2020-11-20 20:48       ` Kees Cook
2020-11-22 16:17       ` Kees Cook
2020-11-22 18:21         ` James Bottomley
2020-11-22 18:25           ` Joe Perches
2020-11-22 19:12             ` James Bottomley
2020-11-22 19:22               ` Joe Perches
2020-11-22 19:53                 ` James Bottomley
2020-11-23 13:03                   ` [Intel-wired-lan] " Gustavo A. R. Silva
2020-11-23 16:31                     ` James Bottomley
2020-11-24 21:32                       ` Kees Cook
2020-11-24 22:24                         ` Finn Thain
2020-11-24 23:15                           ` Miguel Ojeda
2020-11-24 23:53                             ` Finn Thain
2020-11-25  1:05                               ` Miguel Ojeda
2020-11-25  7:05                         ` James Bottomley
2020-11-25 12:24                           ` Nick Desaulniers
2020-11-25 21:33                             ` Finn Thain
2020-11-25 22:09                               ` Nick Desaulniers
2020-11-25 23:21                                 ` Finn Thain
2020-11-26  0:30                                 ` Finn Thain
     [not found]                             ` <20201125082405.1d8c23dc@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
2020-11-25 17:04                               ` Miguel Ojeda
2020-11-25 22:09                               ` Nick Desaulniers
2020-11-25 21:10                           ` Kees Cook
2020-11-22 20:35           ` Miguel Ojeda
2020-11-22 22:36             ` James Bottomley
2020-11-23 14:19               ` Miguel Ojeda
2020-11-23 15:58                 ` James Bottomley
2020-11-23 16:24                   ` Rafael J. Wysocki
2020-11-23 16:32                   ` Joe Perches
2020-11-23 18:56                   ` Miguel Ojeda
2020-11-23 20:37                     ` James Bottomley
2020-11-25  0:32                       ` Miguel Ojeda
2020-11-25 22:44                         ` Edward Cree
2020-11-26 14:53                           ` Miguel Ojeda
2020-11-26 15:28                             ` Geert Uytterhoeven
2020-11-26 16:18                               ` Karol Herbst
2020-11-26 17:05                               ` Miguel Ojeda
2020-11-25 10:38                       ` Andy Shevchenko
2020-11-25  9:01                   ` Sean Young
2020-11-22 22:54             ` Finn Thain
2020-11-22 23:04               ` James Bottomley
2020-11-23 14:05               ` Miguel Ojeda [this message]
2020-11-24  0:58                 ` Finn Thain
2020-11-24  1:05                   ` Joe Perches
2020-11-24  2:48                     ` Finn Thain
2020-11-24 23:46                   ` Miguel Ojeda
2020-11-22 22:10           ` Sam Ravnborg
2020-11-24  1:32         ` Nick Desaulniers
2020-11-24 21:25           ` Kees Cook
2020-11-25 23:02             ` Edward Cree
2020-12-01 14:08           ` Dan Carpenter
2020-12-01 14:04         ` Dan Carpenter
2020-11-20 22:21 ` Miguel Ojeda
2020-11-23 20:03 ` Jason Gunthorpe
2020-11-24 14:47   ` Gustavo A. R. Silva
     [not found] ` <160616392671.21180.16517492185091399884.b4-ty@kernel.org>
2020-11-24 14:47   ` Gustavo A. R. Silva
2020-12-01  5:52 ` Martin K. Petersen
2020-12-01  8:20   ` Gustavo A. R. Silva
2020-12-08  4:52 ` (subset) " Martin K. Petersen

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